Mobile floor cleaner with cleaning solution generator

ABSTRACT

A mobile floor cleaner that includes a moveable housing, a cleaning head operably supported by the moveable housing, one or more solution generators configured to receive a feed liquid and to generate a cleaning solution from the feed liquid by application of acoustic energy and/or nanobubble generation, and control electronics configured to operate the one or more solution generators.

CROSS-REFERENCE

This application claims priority to U.S. Provisional Patent ApplicationNo. 61/987,799, filed May 2, 2014, and U.S. Provisional PatentApplication No. 62/068,426, filed Oct. 24, 2014. The entire contents ofthese applications are incorporated herein by reference.

FIELD

The present disclosure relates to cleaning machines, such as mobilefloor cleaners. In particular, the present disclosure relates to mobilefloor cleaners that incorporate acoustic energy and/or nanobubblegeneration.

BACKGROUND

Floor cleaning in public, commercial, institutional and industrialbuildings have led to the development of various specialized floorcleaning machines, such as hard and soft floor cleaning machines. Thesecleaning machines generally utilize a cleaning liquid dispensing systemand a cleaning head to perform a floor cleaning operation.

The cleaning liquid dispensing system generally dispenses a cleaningliquid that includes water and a chemically based detergent. Thedetergent typically includes a solvent, a builder, and a surfactant. Thecleaning head typically includes one or more disc-type scrubbingbrushes, which may be located in front of, under or behind the floorcleaning machine. The scrubbing brushes typically include nylonbristles, pads or other fibers. The scrubbing brushes are motorized torotate during cleaning operations. The rotation of the scrubbing brushescauses the brushes to scrub the surface being cleaned as they engage thesurface.

While detergents increase cleaning effectiveness for a variety ofdifferent soil types, such as dirt and oils, these detergents also havea tendency to leave unwanted residue on the cleaned surface. Suchresidue can adversely affect the appearance of the surface and thetendency of the surface to re-soil. Additionally, the detergents may notbe environmentally friendly. Some mobile floor cleaning machines havebeen fitted with electrolysis cells for producing anelectrochemically-activated cleaning liquid by electrolyzing a feedliquid such as tap water.

Improved floor cleaning heads, mobile floor cleaners, and floor cleaningmethods are desired for reducing the use of detergents during cleaningoperations, while maintaining the efficacy of the floor cleaningoperation.

SUMMARY

An aspect of the present disclosure is directed to a mobile floorcleaner that includes a moveable housing, a cleaning head operablysupported by the moveable housing, a liquid source configured to providea feed liquid, and a conduit configured to relay the feed liquid fromthe liquid source. The mobile floor cleaner also includes one or moresolution generators configured to receive the feed liquid from theconduit, and to generate a cleaning solution from the feed liquid byapplication of acoustic energy (e.g., via ultrasonic waves) andnanobubble generation (e.g., via electrolysis). The mobile floor cleanerfurther includes control electronics configured to operate the one ormore solution generators.

Another aspect of the present disclosure is directed to a method forcleaning a surface. The method includes providing a mobile floor cleanerhaving a cleaning head and a solution generator, directing a flow of afeed liquid to the solution generator, and generating a cleaningsolution by applying acoustic energy to and generating nanobubbles inthe feed liquid in the solution generator. The method also includesdispensing the generated cleaning solution to the surface, and agitatingthe dispensed cleaning solution with the cleaning head.

Another aspect of the present disclosure is directed to a mobile floorcleaner that includes a moveable housing, a liquid source configured toprovide a feed liquid, a conduit configured to relay the feed liquidfrom the liquid source, and a scrubbing brush operably supported by themoveable housing. The scrubbing brush includes a backing portion, one ormore sub-units each configured to retain a set of bristles, and one ormore transducers supported by the backing portion and configured tovibrate the one or more sub-units and retained sets of bristles. Themobile floor cleaner also includes control electronics configured tooperate the one or more transducers.

DEFINITIONS

Unless otherwise specified, the following terms as used herein have themeanings provided below:

The terms “preferred” and “preferably” refer to embodiments of theinvention that may afford certain benefits, under certain circumstances.However, other embodiments may also be preferred, under the same orother circumstances. Furthermore, the recitation of one or morepreferred embodiments does not imply that other embodiments are notuseful, and is not intended to exclude other embodiments from the scopeof the present disclosure.

The term “providing”, such as for “providing a mobile floor cleaner”,when recited in the claims, is not intended to require any particulardelivery or receipt of the provided item. Rather, the term “providing”is merely used to recite items that will be referred to in subsequentelements of the claim(s), for purposes of clarity and ease ofreadability.

The terms “about” and “substantially” are used herein with respect tomeasurable values and ranges due to expected variations known to thoseskilled in the art (e.g., limitations and variabilities inmeasurements).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side schematic illustration of an example mobile floorcleaner of the present disclosure.

FIG. 2 is a top perspective view of a cleaning head of the mobile floorcleaner.

FIG. 3 is an exploded top perspective view of a scrubbing brush of thecleaning head shown in FIG. 2.

FIG. 4 is a side schematic illustration of the scrubbing brush with asolution generator having a transducer unit located upstream from anelectrolysis cell.

FIG. 5A is a side schematic illustration of the scrubbing brush with analternative solution generator having an electrolysis cell locatedupstream from a transducer unit.

FIG. 5B is a side schematic illustration of the example mobile floorcleaner of FIG. 1 showing an alternative solution generatorconfiguration.

FIG. 6 is a top schematic illustration of an alternative scrubbing brushof the cleaning head, which includes radial rows of multiple solutiongenerators.

FIG. 7 is a side schematic illustration of the alternative scrubbingbrush shown in FIG. 6.

FIG. 8 is a side schematic illustration of an alternative cleaning headhaving multiple front-located solution generators.

FIG. 9 is a top schematic illustration of the alternative cleaning headshown in FIG. 8.

FIG. 10 is a top schematic illustration of an alternative scrubbingbrush having bristles secured to multiple transducer sub-units.

FIG. 11 is a side schematic illustration of the alternative scrubbingbrush shown in FIG. 10.

FIG. 12 is a side schematic illustration of a second example mobilefloor cleaner of the present disclosure having multiple solutiongenerators separate from the cleaning head.

FIG. 13 is a schematic illustration of a third example mobile floorcleaner of the present disclosure having multiple solution generatorsseparate from a dual-roller cleaning head.

FIG. 14 is a front perspective view of an alternative cleaning headhaving a cylindrical member.

FIG. 15 is an exploded perspective view of the alternative cleaning headshown in FIG. 14.

FIG. 16 is an illustration of an example portable cleaning stick thatincludes a solution generator for applying localized cleaning fluid.

DETAILED DESCRIPTION

The present disclosure is directed to a mobile floor cleaner thatincludes an acoustic transducer (e.g., an ultrasonic transducer) and/ora nanobubble generator (e.g., with an electrolysis cell or othernanobubble generator), which produce a cleaning solution from an aqueousfeed liquid, such as water. As discussed below, the acoustic transducerand/or the nanobubble generator, in combination with a floor cleaninghead, allows the mobile floor cleaner to clean floor surfaceseffectively with little or no additives (e.g., detergents), andpreferably with low power consumption. The lower power consumptioncorrespondingly allows the mobile floor cleaner to incorporate smallerand/or fewer batteries with sustainable operating durations.

FIG. 1 illustrates an example mobile floor cleaner 10 of the presentdisclosure, which may be designed for use by an operator that walksbehind the machine or rides on the machine. Examples of suitablecleaning units for mobile floor cleaner 10 include the “T”-seriesscrubbers from Tennant Company, Minneapolis, Minn., which are modifiedto operate as discussed below. Alternatively, mobile floor cleaner 10may be configured to be towed behind another vehicle.

As shown, mobile floor cleaner 10 includes housing 12, which issupported by wheels 14 that advance mobile floor cleaner 10 in thedirection of arrow 16 along a surface to be cleaned, such as surface 18.One or more of wheels 14 are correspondingly rotated by motor 20 basedon operator commands, where motor 20 may include one or more electricmotors and/or an internal combustion engine. Motor 20 may also beconfigured to rotate wheels 14 in the opposing directions to reverse themovement of mobile floor cleaner 10.

As further shown, mobile floor cleaner 10 also includes cleaning head22, which, in the shown example, is a disc-type, scrubbing brush headthat includes cover or shroud 24 and rotatable scrubbing brush 26.Scrubbing brush 26 is rotated about an axis of rotation 28 relative tocover 24 by motor 30. Motor 30 may include one or more electric motorsthat generate rotational power for a drive shaft or other mechanism (notshown) that extends along axis 28. Preferably, axis 28 is substantiallyperpendicular to the surface 18 being cleaned, allowing scrubbing brush26 to rotate parallel to the surface 18 being cleaned.

Mobile floor cleaner 10 also includes control electronics 32, whichinclude one or more control circuits configured to monitor and operatethe components of mobile floor cleaner 10 over one or more control lines(e.g., electrical, optical, and/or wireless lines, not shown). Controlelectronics 32 and the components of mobile floor cleaner 10 arepreferably powered from batteries 34, which are one or more rechargeablebatteries, allowing mobile floor cleaner 10 to move freely withoutrequiring a physical connection to a fixed electrical outlet.Accordingly, control electronics 32 may direct the operation of motors20 and 30 respectively over control lines 36 and 38.

One or more of the control functions performed by control electronics 32can be implemented in hardware, software, firmware, or a combinationthereof. Such software, firmware, and the like may be stored on anon-transitory computer-readable medium, such as a memory device. Anycomputer-readable memory device can be used, such as a disc drive, asolid state drive, CD-ROM, DVD, flash memory, RAM, ROM, a set ofregisters on an integrated circuit, and/or the like. For example, thecontrol circuit can be implemented partly or completely in aprogrammable logic controller and/or a processing device such as amicrocontroller and/or other processor that executes instructions storedin a memory device, where the instructions configure the processor toperform the steps of the control process when executed by the processorto convert the processor into a special purpose computer.

Mobile floor cleaner 10 also includes liquid source 40, which is one ormore reservoirs or tanks for storing a feed liquid 42 for cleaning,and/or may include a fitting or other inlet for receiving feed liquid 42from an external source (e.g., from an external hose). Feed liquid 42 isan aqueous liquid, preferably regular, untreated tap water or otherwater that is commonly available. In some embodiments, feed liquid 42may include one or more electrolytes to assist in an electrolysisreaction.

In some alternative situations, feed liquid 42 may also include one ormore additives, such as detergents, which preferably do not leavepost-cleaning residues and do not chemically attack the cleaned surface18. However, as indicated above, in preferred embodiments, feed liquid42 is substantially free of any residue-forming additives, such asdetergents.

Feed liquid 42 may exit liquid source 40 by conduit 44, which mayinclude one or more actuatable valves (e.g., valve 46) and/or pumps(e.g., pump 48) for supplying feed liquid 42 to cleaning head 22.Control electronics 32 may direct the operation of valve 46 and/or pump48 respectively over control lines 50 and 52. In alternativeembodiments, feed liquid 42 may be supplied from liquid source 40 by theoperation of gravity, without pump 48.

Conduit 44 directs feed liquid 42 to solution generator 54, which, inthe shown embodiment, includes transducer unit 56 and nanobubblegenerator (e.g., electrolysis cell) 58. As discussed below, transducerunit 56 includes one or more acoustic transducers configured to generatehigh-frequency acoustic waves through the received feed liquid 42. Theacoustic transducers may be any suitable transducer, such aspiezoelectric transducers and/or magnetostrictive transducers, andpreferably generate ultrasound waves (e.g., from about 20 kilohertz toabout 400 kilohertz).

The generated acoustic waves create compression waves in the receivedfeed liquid 42 that flows through transducer unit 56, which producemicroscopic voids or bubbles. Feed liquid 42 preferably fills the volumeof transducer unit 56 at all times during operation to prevent theformation of air pockets that can otherwise potentially disrupt theacoustic waves.

After passing through transducer unit 56, the resulting liquid flowsthrough nanobubble generator 58. Nanobubble generator 58 can beimplemented as an electrolysis cell that generates nanobubbles in theflowing liquid through electrolysis. Examples of suitable cells for anelectrolysis cell nanobubble generator 58 include those disclosed inU.S. Pat. No. 8,156,608. In alternative embodiments, nanobubblegenerator 58 may be replaced with other nanobubble generators, such asmechanical nanobubble generators (e.g., air infiltration sieves, venturinozzles, swirl nozzles). These nanobubble generators can generatenanobubbles through shear forces without application of electricalenergy. Therefore, although various example configurations describedherein are described as having an electrolysis cell 58, theconfigurations may be implemented using a mechanical nanobubblegenerator in addition to or in lieu of electrolysis cell 58 withoutdeparting from the scope of the disclosure.

The flowing liquid received from transducer unit 56 also preferablyfills the volume of electrolysis cell 58 at all times during operationto maintain the electrolysis reaction. Accordingly, transducer unit 56and electrolysis cell 58 are each preferably sized based on thevolumetric flow rate of feed liquid 42 to solution generator 54, whichis accordingly dependent on the dimensions of conduit 44 and operationalrate of pump 48.

The resulting cleaning solution that is generated may then exitelectrolysis cell 58 (or other nanobubble generator) via a dispensingnozzle or orifice 60. The dispensed cleaning solution preferablyprovides a suitable path for conducting the acoustic waves (e.g.,ultrasonic waves) from transducer unit 56 to the surface 18 beingcleaned, through the dispensed cleaning solution. The dispensed cleaningsolution also preferably carries the entrained nanobubbles to thesurface 18 being cleaned.

Control electronics 32 may direct the operation of solution generator 54(i.e., transducer unit 56 and electrolysis cell 58) over control line62. In the shown embodiment, solution generator 54 is retained byscrubbing brush 26 of cleaning head 22 at its axial location. While notwishing to be bound by theory, it is believed that having the flow ofthe cleaning solution traverse around conduit corners or other conduitbends can adversely affect the stability of the generated cleaningsolution, which can potentially reduce its cleaning efficiency.Therefore, solution generator 54 is preferably located close to anddirected towards the surface being cleaned (e.g., surface 18) topreserve the cleaning effectiveness. This is believed to provide asuitable path for conducting the acoustic waves (e.g., ultrasonic waves)and for carrying the entrained nanobubbles from solution generator 54 tothe surface 18 being cleaned, through the dispensed cleaning solution.

The arrangement shown in FIG. 1, with solution generator 54 at the axiallocation of scrubbing brush 26, provides a suitable arrangement fordispensing the cleaning solution directly onto surface 18, and thenagitating the cleaning solution with the rotating scrubbing brush 26after the initial dispensing. This is believed to allow the generatedbubbles from transducer unit 56 and electrolysis cell 58 to attract toand/or dislodge the contaminants (e.g., dirt) on surface 18 prior tobeing agitated with the rotating bristles of scrubbing brush 26. Therotating bristles may then abrasively remove the contaminants along withthe cleaning solution to clean surface 18.

As discussed below, solution generator 54 may rotate with scrubbingbrush 26 while scrubbing brush 26 is driven by motor 30. As such,solution generator 54 may be a sacrificial unit that is permanentlyattached to the scrubbing brush 26, and the elements of transducer unit56 and electrolysis cell 58 may be integrated within scrubbing brush 26such that the brush and solution generator 54 are fabricated together asa single, unitary part. Alternatively, solution generator 54 may befabricated as separate components that are secured to scrubbing brush26.

Mobile floor cleaner 10 may also include a recovery system 64, which, inthe shown embodiment, includes one or more vacuum units 66, one or morevacuum extractor tools 68, one or more vacuum squeegees 70, a vacuumpath selector 72, and one or more waste recovery tanks 74. Vacuum unit66 is used in combination with vacuum extractor tool 68 and/or vacuumsqueegee 70 to remove liquid and solid waste (i.e., soiled cleaningliquid) from surface 18. Control electronics 32 may direct operation ofvacuum unit 66 over control line 75.

Vacuum extractor tool 68 may be used for removing liquid and soliddebris from soft surfaces 18, whereas vacuum squeegee 70 may be used forremoving liquid and solid debris from hard surfaces 18, for example.Other types of liquid and debris recovery tools and methods can also beused for use on hard surfaces, soft floor surfaces, or both. Mobilefloor cleaner 10 may also include one or more lift mechanisms (notshown) operated by control electronics 32 to independently raise andlower vacuum extractor tool 68 and vacuum squeegee 70.

The waste is passed through vacuum path selector 72 and into wasterecovery tank 74. Vacuum path selector 72 allows a single vacuum unit 66to selectively couple to vacuum extractor tool 68 and vacuum squeegee70. Alternatively, separate vacuum units 66 may be individually used forvacuum extractor tool 68 and vacuum squeegee 70. In this alternativeembodiment, vacuum path selector 72 may be optionally omitted.

During a cleaning operation, control electronics 32 may energize motor30 (via control line 38) to rotate scrubbing brush 26 about axis 28,open valve 46 (via control line 50), and energize pump 48 (via controlline 52) to supply the feed liquid 42 through conduit 44 to solutiongenerator 54. Control electronics 32 may also energize the acoustictransducers in transducer unit 56 to generate acoustic waves (e.g.,ultrasonic waves) through the feed liquid 42 flowing through transducerunit 56.

Control electronics 32 may also energize electrolysis cell 58 togenerate nanobubbles in the liquid that passes through the cell 58 viaelectrolysis. In particular, control electronics 32 may energizeelectrolysis cell 58 by applying a suitable voltage across theelectrodes contained in the cell. Electrolysis cell 58 accordinglygenerates an electrolyzed cleaning liquid that is dispensed directlyonto surface 18 at an axially-central location along axis 28 (viadispensing nozzle 60). The electrically-charged nanobubbles of theresulting cleaning solution then attract and dislodge contaminants fromsurface 18, allowing the contaminants to then be abrasively removed bythe rotation of scrubbing brush 26. The resulting soiled solution withthe contaminants may then be collected with recovery system 64.

While not wishing to be bound by theory, it is believed that thecombination of the acoustic energy (via transducer unit 56) with thegenerated nanobubbles at electrolysis cell 58 (or other nanobubblegenerator) generate a cleaning solution that is effective for attractingand dislodging contaminants from surfaces (e.g., surface 18).Additionally, transducer unit 56 and electrolysis cell 58 are each lowpower-consuming devices. As such, solution generator 54 is suitable forgenerating cleaning solutions (free of detergents) without consumingsubstantial amounts of electrical power. This accordingly preserves theoperating duration of mobile floor cleaner 10 and/or allows smaller orfewer batteries 34 to be used.

In addition, although the combination of acoustic energy and nanobubblesgenerated at electrolysis cell 58 can be used to provide an efficaciouscleaning solution, it should be appreciated that mobile floor cleaner 10can be configured to clean using acoustic energy without generatednanobubbles or generated nanobubbles without acoustic energy. Dependingon the application, the cleaning efficacy provided by the acousticenergy enhancement or nanobubbles enhancement of feed liquid 42 alonemay be sufficient to adequately clean a desired surface (e.g., surface18). Therefore, although mobile floor cleaner 10 in the example of FIG.1 is described as using the combination of the acoustic energy (viatransducer unit 56) with the generated nanobubbles at electrolysis cell58, it should be appreciated that the disclosure is not limited to thiscombination of features.

In practice, it is believed that dispensing the generated cleaningsolution directly onto surface 18 without initially flowing into therotating bristles of scrubbing brush 26 preserves the cleaningeffectiveness of the generated cleaning solution for attracting anddislodging contaminants from surface 18. Shortly after being dispensedonto surface 18, scrubbing brush 26 may then further assist in thecleaning efforts through mechanical abrasion. This results in a cleansurface 18 that is substantially free of film-forming residues.

FIG. 2 illustrates an example embodiment for cleaning head 22 with theintegrated solution generator 54, and where cleaning head 22 isconfigured to carry a single, disc-type scrubbing brush 26. As shown,cover 24 is attached to a stationary part of motor 30. Cover 24 has asubstantially closed upper surface 76, and a substantially open lowersurface 78 facing the surface 18 to be cleaned. Scrubbing brush 26 iscarried underneath cover 24 and is connected to a drive shaft or othermechanism (not shown) of motor 30, which extends through an aperture 80at the axial center of upper surface 76.

In addition, cleaning head 14 includes conduit 82 having a first endconfigured to be connected to conduit 44 (shown in FIG. 1) for receivingfeed liquid 42 from liquid source 40. A second end of conduit 82 passesthrough the aperture 80 to deliver feed liquid 42 to solution generator54 (not shown in FIG. 2) incorporated into scrubbing brush 26. Cover 24further includes an electrical terminal block 84, which provides anelectrical connection to control line 62 (shown in FIG. 1) for operatingsolution generator 54. As explained in further detail below, cover 24also provides a connection from terminal block 84 to correspondingelectrical conductors on scrubbing brush 26.

FIG. 3 illustrates scrubber brush 26, which includes adapter 86 (alsoknown as a disc hub or receiver), which attaches scrubbing brush 26 tothe drive shaft of motor 30. Adapter 86 includes a central, female hubcoupling 88, which is configured to receive and fixedly connect to thedrive shaft of motor 30. Adapter 86 may be connected to the drive shaftby a bolt passing axially through the coupling 88 or a set screw withincoupling 88, for example. Other methods of attachment may also be used.

Adapter 86 further includes a plurality of slots 90 configured toreceive corresponding studs or cleats 92 attached to a backing portion94 of scrubbing brush 26, by a friction fit, for example. A retainingspring 96 may also be provided to maintain the brush studs 92 engagedwithin slots 90. Studs 92 form a mechanical connection configured toreceive a rotating driving force through adapter 86 to rotate scrubbingbrush 26.

Adapter 86 also includes an annular slot 98 around coupling 88, whichincludes multiple reinforcing ribs. Annular slot 98 allows the receivedfeed liquid 42 flowing from the second end of conduit 82 to falldownward past adapter 86. This allows the feed liquid 42 to reachsolution generator 54 despite the high-speed rotation of scrubbing brush26 (including adapter 86).

Scrubbing brush 26 also includes a set of bristles or other scrubbingmaterial 100 attached to backing portion 94. Backing portion 94 can beformed of any suitable material such as plastic, synthetic material,wood, metal, and the like. In a particular example, backing portion 94is formed of a rigid plastic material through an injection moldingprocesses. Bristles 100 may be attached in any suitable manner to thelower surface of backing portion 94. In one example, bristles 100 aremolded within the material of backing portion 94. Other attachmentmethods may also be used, such as adhesives or heat sealing.

Bristles 100 can be made of any suitable material such as plastic (e.g.,nylon, polyester, polypropylene), natural animal hair (e.g. horse or hoghair), metal fibers, abrasives, and the like. Also, bristles 100 may begenerally aligned vertically as shown in FIG. 3 or may be interconnectedor layered such as in a pad form.

Backing portion 94 also includes a central aperture 102 in whichsolution generator 54 resides, below mesh plate 104, where mesh plate104 maybe omitted in some embodiments. During operation, the feed liquid42 flows through annular slot 98 and mesh plate 104, and into transducerunit 56 of solution generator 54. This arrangement allows transmissionof the feed liquid 42 into solution generator 54 despite the high-speedrotation of scrubbing brush 26, as mentioned above.

Backing portion 94 also includes an electrical coupling, such as firstand second electrical conductors or contacts 106 and 108, which areelectrically connected to transducer unit 56 and electrolysis cell 58.In this example, electrical conductors 106 and 108 are formed ascoaxial, annular rings on backing portion 94. These rings are engaged bycorresponding electrical brushes 110 carried by the lower surface 78 ofcover portion 24, and which are connected to terminal block 84 of coverportion 24. In an alternative embodiment, the electrical conductors 106and 108 are carried by cover portion 24, and the electrical brushes 110are carried by backing portion 94.

As scrubbing brush 26 rotates around axis 28 within cover portion 24,the electrical brushes 110 maintain electrical contact with electricalconductors 106 and 108. The conductors 106 and 108 and brushes 110 canbe located at any radius on the upper surface of backing portion 94,along the periphery of backing portion 94, and/or anywhere on adapter86, for example. In another embodiment, the electrical connectionbetween terminal block 86 and electrodes 106 and 108 is made by aninductive coupling, where a first member of the coupling is attached tocover portion 24 and a second member of the coupling is attached toadapter 86 or backing portion 94, for example. Other types of electricalcouplings may be used in other embodiments.

As noted above, transducer unit 56 is configured to generatehigh-frequency acoustic waves in feed liquid 42, such as waves having afrequency greater than 20 kilohertz. In general, transducer unit 56 canbe implemented using any type of acoustic wave generator that convertselectrical energy into sound waves. In one example, transducer unit 56includes one or more piezoelectric transducers that utilize thepiezoelectric property of a material to convert electrical pulses intomechanical vibrations. In another example, transducer unit 56 includesone or more magnetostrictive transducers that utilize themagnetostrictive property of a material to convert electrical pulsesinto mechanical vibrations.

FIG. 4 is an additional simplified illustration of the engagementbetween solution generator 54 and scrubbing brush 26. As shown,transducer unit 56 of solution generator 54 may be secured withinaperture 102 below mesh plate 104, where transducer unit 56 includes oneor more acoustic transducers 112 for generating the acoustic waves(e.g., ultrasonic waves) in the received feed liquid 42, as discussedabove. Beneath transducer unit 56, electrolysis cell 58 may also besecured within aperture 102, and held in place with dispensing nozzle60, which may function as a restraining cap for solution generator 54.

Electrolysis cell 58 includes first and second electrodes 114 and 116,which in the example shown in FIG. 4, are arranged parallel to andseparated from one another by a suitable gap (e.g., with spacer 118) toelectrically isolate each other. Thus, electrodes 114 and 116 areoriented in planes that are parallel to the face of bristles 100 thatengage the surface 18 being cleaned. In this embodiment, electrodes 114and 116 are mesh-type electrodes, which enable the liquid fromtransducer unit 56 to pass through electrodes 114 and 116 by the forceof gravity. In alternative embodiments, electrodes 114 and 116 may eachbe an annular electrode that is concentric with axis 28, allowing theliquid from transducer unit 56 to flow between the electrodes 114 and116.

During operation, control electronics 32 activate acoustic transducers112, and apply a suitable voltage potential across electrodes 114 and116, via control line 62, terminal block 84, electrical brushes 110, andconductors 106 and 108. Feed liquid 42 is supplied to transducer unit 56through conduits 44 and 82, aperture 80, annular slot 98, and mesh plate104.

As motor 30 rotates scrubbing brush 26 about axis 28, the feed liquid 42flows through transducer unit 56 and electrolysis cell 58 to generatethe cleaning solution, as discussed above. In particular, acoustictransducers 112 preferably create ultrasonic waves through the flowingfeed liquid 42, which then flows into electrolysis cell 58. Atelectrolysis cell 58, as the received liquid passes between theelectrodes 114 and 116, the applied voltage induces an electricalcurrent through the liquid contained in the gap and further generatesnanobubbles in the liquid.

Due to gravity, the generated cleaning solution exits electrolysis cell58 through dispensing nozzle 60, and is directly dispensed onto surface18. As further shown in FIG. 4, after entering transducer unit 56, thefeed liquid 42 preferably flows along a straight flow path thoughtransducer unit 56, electrolysis cell 58, and dispensing nozzle 60, andonto surface 18. This allows the generated cleaning solution to bedispensed with a straight and direct flow path onto surface 18.

After being dispensed, the mechanical action of bristles 100 dispersesthe cleaning solution beneath brush 26 to actively clean surface 18. Ina particular example, motor 30 may rotate scrubbing brush 26 from about200 rotations per minute (rpm) to about 400 rpm, such as at about 300rpm.

An exemplary technical effect of incorporating the solution generator 54in the scrubbing brush 26 is that the feed liquid 42 is conditioned veryclose to the point of use at the surface 18 being cleaned, at the veryend of the liquid flow path. This limits neutralization of the generatedcleaning solution from the time at which the liquid is conditioned bysolution generator 54 to the time at which the liquid contacts thesurface 18 being cleaned.

In an alternative embodiment, transducer unit 56 may be separate fromelectrolysis cell 58, where transducer unit 56 may be retained at anysuitable location upstream from scrubbing brush 26 (e.g., secured tocover 24). In this case, electrolysis cell 58 may be retained at anysuitable location downstream from transducer unit 56, such as atscrubbing brush 26, as shown.

FIG. 5A illustrates an alternative embodiment for solution generator 54,where nanobubble generator 58 (e.g., an electrolysis cell) is locatedupstream relative to transducer unit 56. In this embodiment, thereceived feed liquid 42 initially undergoes electrolysis to generatenanobubbles in electrolysis cell 58, and the resulting liquid is thensubjected to the ultrasonic waves of transducer unit 56 before beingdispensed.

In a further embodiment, electrolysis cell 58 may be separate fromtransducer unit 56, where electrolysis cell 58 may be retained at anysuitable location upstream from scrubbing brush 26. For example,electrolysis cell may be retained at a location along conduit 44 and/orsecured to cover 24. In this case, transducer unit 56 may be retained atany suitable location downstream from electrolysis cell 58, such as atscrubbing brush 26, as shown.

FIG. 5B illustrates an alternative embodiment of mobile floor cleaner 10where like reference numbers refer to like elements discussed above inconnection with FIGS. 1-4. In the example of FIG. 5B, mobile floorcleaner 10 includes a solution generator 54 that has a transducer unit56 but which does not contain a nanobubble generator (such aselectrolysis cell 58). Transducer unit 56 is located in fluidcommunication with feed liquid 42 via conduit 44. In operation,transducer unit 56 can receive feed liquid 42 from liquid source 40 andimpart acoustic energy to the feed liquid to generate anacoustically-enhanced liquid. For example, operating under the controlof control electronics 32, transducer unit 56 can generate acousticwaves that are passed into feed liquid 42 flowing through solutiongenerator 54. The acoustically-enhanced liquid generated by solutiongenerator 54 can then be dispensed onto a surface to be cleaned viadispensing nozzle or orifice 60.

The acoustic energy imparted to feed liquid 42 can enhance the cleaningefficacy of the liquid as compared to when the liquid is not treatedwith acoustic energy. Acoustic waves generated by transducer unit 56 canpropagate through feed liquid 42 as longitudinal waves that compress anddecompress in the direction of travel. The compression and decompressionof the acoustic waves can generate cavitation bubbles or void spaceswithin feed liquid 42. These cavitation bubbles or void spaces, whichmay or may not have a mean diameter less than 1 nanometer, can increasecleaning efficacy by agitating feed liquid 42 and creating a scrubbingaction. For example, when the cavitation bubbles or void spaces implode,which can occur when the acoustically-enhanced liquid contacts a surfaceto be cleaned, the implosion can generate an intense localizedshockwave. The shockwave can provide a force sufficient to overcomecontaminant-to-substrate adhesion forces, releasing contaminants andcleaning the target surface.

When solution generator 54 is configured with transducer unit 56 butwithout a nanobubble generator as shown in FIG. 5B, one or moreacoustical transducers can be positioned in a number of different waysto direct acoustic energy into feed liquid 42. For example, thetransducers can be positioned adjacent to and, in some examples, incontact with feed liquid 42 as it flows from liquid source 40 todispensing nozzle or orifice 60. In such examples, the transducers candirect acoustic energy into feed liquid 42 prior to applying the liquidto a surface to be cleaned. Additionally or alternatively, thetransducers can be positioned to direct acoustic energy into feed liquid42 after the liquid has been applied to a surface to be cleaned. In suchexamples, the liquid can be discharged via dispensing nozzle or orifice60 onto a surface to be cleaned and thereafter impacted with acousticenergy generated by transducer unit 56. FIGS. 6 and 7 illustrate analternative embodiment for scrubbing brush 26, which includes multiplesolution generators 54 arranged radially around backing portion 94between groups of bristles 100. As further shown in FIG. 7, backingportion 94 may also include conduits 120 for directing the received feedliquid 42 from aperture 102 to the individual solution generators 54 viacentrifugal force and gravity.

In this embodiment, the number, sizes, and arrangements of the multiplesolution generators 54 may vary depending on the particular cleaningrequirements. As can be appreciated, due the increased number ofsolution generators 54 in this embodiment, they each may be smaller insize than the single, axially-located solution generator shown in FIGS.1-5. Furthermore, the number of radial rows of the multiple solutiongenerators 54 may vary, such as from one row to ten rows, or from tworows to six rows, or from three rows to five rows.

Additionally, while illustrated as liner rows of multiple solutiongenerators 54, each radial row may alternatively extend in any suitablearrangement, such as with spiral arms. This embodiment shown in FIGS. 6and 7, and its variations, allow the generated cleaning solution to bedispensed in situ with the rotating bristles 100. For many applications,this can further assist in the cleaning efficiency of mobile floorcleaner 10.

FIGS. 8 and 9 illustrate another alternative embodiment in whichmultiple solution generators 54 are secured to cover 24 at a locationthat is in front of scrubbing brush 26 (in the direction of movementillustrated by arrow 16). In this embodiment, conduit 44 and controlline 62 may each branch into each of the solution generators 54 forindependent or collective operation.

The number, sizes, and arrangements of the multiple solution generators54 in this embodiment may also vary depending on the particular cleaningrequirements. Preferably, the multiple solution generators 54 in thisembodiment produce a sufficient quantity of the generated cleaningsolution to function with the size of scrubbing brush 26. As can beappreciated, due the increased number of solution generators 54 in thisembodiment, they each may also be smaller in size than the single,axially-located solution generator shown in FIGS. 1-5. Examples ofsuitable numbers of solution generators 54 in this embodiment range fromone to ten, or from two to eight, or from four to six.

As shown in FIG. 9, the multiple solution generators 54 are arranged oncover 24 of cleaning head 22 in an arced row in front of scrubbing brush26 (in the movement direction of arrow 16). Alternatively, the multiplesolution generators 54 may be arranged in any suitable manner, such as alinear row, a staggered row, and the like.

FIGS. 10 and 11 illustrate another embodiment, which may utilized inaddition to the embodiments shown in FIGS. 1-9 (as well as in FIG. 12)and/or alternatively to the shown embodiments. As shown in FIG. 10,scrubbing brush 26 may also include multiple tracks, blocks, or othersub-units 122 that are supported by backing portion 94, but are capableof vibrating relative to backing portion 94. In particular, eachsub-unit 122 is molded with or otherwise retains a group of bristles100, and is engaged with one or more transducing elements 124 (e.g., asshown in FIG. 11).

The number and dimensions of sub-units 122 may be selected to optimizethe placement of bristles 100. Each sub-unit 122 is preferably sizedsuch that the associated transducing element(s) 124 are capable ofgenerating sufficient vibrations. While illustrated as rectangulartracks, each sub-unit 122 may have any suitable geometric shape (e.g.,square, round, etc. . . . ) and size, and sub-units 122 of differentshapes and sizes may be used together to increase the covered surfacearea of scrubbing brush 26. Additional bristles 100 may also be moldedor otherwise secured to backing portion 94 between the sub-units 122 toincrease the brushing capabilities while rotating.

Each transducing element 124 may receive electrical power from contacts106 and 108, as discussed above, and is configured to vibrate at a highfrequency, such as at an ultrasonic frequency, for example (e.g., fromabout 20 kilohertz to about 400 kilohertz). This can assist in removingcontaminants from surface 18 with or without rotation. Accordingly, insome embodiments, the high-frequency vibrations are used in combinationwith the rotation of scrubbing brush 26 (via motor 30). Alternatively,the high-frequency vibrations may be used in lieu of the rotation ofscrubbing brush 26, such as for use on delicate or fragile surfaces 18,for example.

In either case, one or more solution generators 54 may also be used togenerate the cleaning solution, as discussed above. However, in someoptional and alternative embodiments, solution generator 54 may beomitted, and the scrubbing brush 26 with transducing elements 124 may beused with conventional cleaning solutions. In further embodiments, thescrubbing brush 26 with transducing elements 124 may be used incombination with one or more electrolysis cells 58 or other nanobubblegenerators (i.e., transducer units 56 are omitted). This arrangementallows the scrubbing brush 26 with transducing elements 124 to be usedwith a cleaning solution having entrained nanobubbles. As such, thehigh-frequency vibrations of this embodiment may be used with or withoutbrush rotation, with or without solution generator(s) 54, and/or with orwithout electrolysis cells 58 (or other nanobubble generators). Thesealternative combinations increase the versatility of mobile floorcleaner 10.

FIG. 12 illustrates an embodiment that is similar to that shown in FIGS.8 and 9. However, in this embodiment, one or more solution generators 54may be separate from cleaning head 22, and located in front of scrubbingbrush 26 (in the direction of movement illustrated by arrow 16). Forexample, a line or row of multiple solution generators 54 may bepositioned in front of scrubbing brush 26, similar to that shown in FIG.9, but separate from cleaning head 22. Furthermore, the line or row ofmultiple solution generators 54 may be a linear row, an arced row (asillustrated in FIG. 9), a staggered row, and the like. Examples ofsuitable numbers of solution generators 54 in this embodiment range fromone to ten, or from two to eight, or from four to six. One of thebenefits of this design is the ability to retrofit solution generators54 into existing mobile floor cleaners.

FIG. 13 illustrates an embodiment that is similar to that shown in FIG.12, where cleaning head 22 is replaced with cleaning head 122, whichincludes one or more soil transfer rollers or extractor brushes 124 forcleaning soft floors. In this embodiment, recovery system 64 may alsoinclude an additional vacuum extractor tool (not shown) directed atrollers 124.

The rotation of rollers 124 (via motor 30) in the directions indicatedby the arrows results in portions of the rollers 124 being wetted withthe generated cleaning solution, extracted by rollers 124, and wiped orbrushed against surface 18. For example, as rollers 124 rotate, theyengage the soft floor (e.g., carpet fibers) and cause soil to betransferred from the carpet fibers to rollers 124. Rollers 124 arefurther rotated and may optionally be sprayed again by a separate nozzle(not shown). Subsequently, the surfaces of rollers 124 may be vacuumextracted to remove the soiled cleaning liquid from the rollers 124,which is conveyed into recovery tank 74.

As can be seen, the line or row of solution generators 54 in front ofcleaning head 122 may function in the same manner as discussed above forthe embodiment shown in FIG. 12. This also allows existing mobile floorcleaners having cleaning head 122 to be retrofitted to incorporatesolution generators 54.

FIGS. 14 and 15 depict another embodiment that incorporates a cleaninghead 126 as disclosed in U.S. Publication No. 2011/0219555, and which ismodified to incorporate an elongated solution generator. As shown inFIG. 14, cleaning head 126 is configured to dispense the generatedcleaning solution to surface 18 from within the interior of the cleaninghead 126. Cleaning head 126 includes a cylindrical member 128 that isconfigured to engage surface 18 and rotate about a central axis that isparallel to the surface 18 being cleaned, during the performance of thecleaning operation on surface 18.

In one embodiment, the rotation of cylindrical member 128 is notdirectly driven by a motor, such as motor 30. This non-motorizedrotation of cylindrical member 128 means that, unlike conventional floorcleaning heads, no motor is directly coupled to cylindrical member 128through a mechanical linkage of the cleaner, such as a drive belt orgear train, through which the rotation of cylindrical member 128 aboutits axis can be driven. Rather, the rotation of cylindrical member 128is driven solely by engagement of cylindrical member 128 with surface 18as mobile floor cleaner 10 travels across surface 18.

As further shown in FIG. 15, conduit 44 may connect to a transducingdispenser tube 130 within the cylindrical member 128, which may includeone or more apertures or slots distributed along the length of tube 130to allow for substantially even dispensing of the feed liquid 42 to theinterior cavity of the cylindrical member 128. As such, conduit 44delivers a flow of feed liquid 42 into the interior cavity of the tube130.

In the shown embodiment, dispenser tube 130 may include one or moreacoustic transducers (not shown) along its length or at its endlocations to generate acoustic waves (e.g., ultrasonic waves) in thefeed liquid 42 dispensed into the interior cavity of the cylindricalmember 128. In other words, dispenser tube 130 may function as atransducing unit in a similar manner to transducing unit 54 discussedabove.

As further shown, cylindrical member 128 also includes a tubularelectrolysis cell 132, which may function in the same manner asdisclosed in U.S. Publication No. 2011/0219555. Electrolysis cell 132 iscorrespondingly located within a porous and rigid inner cylindrical wall134, and a porous and compressible outer cylindrical wall 136, as alsodisclosed in U.S. Publication No. 2011/0219555.

In particular, the compressibility of the outer cylindrical wall 136 canagitate the surface 18 using the generated cleaning solution withoutsliding contact with surface 18. This occurs as outer cylindrical wall136 is first compressed against surface 18 and then decompressed ascylindrical member 128 rolls over surface 18. The compression of outercylindrical wall 136 causes an initial increase in pressure within itsapertures. This pressure is released when outer cylindrical wall 136decompresses and expands as cylindrical member 128 continues to rotate.This compression and decompression operation moves the generatedcleaning solution proximate to the apertures, which encourage therelease of dirt on surface 18 for later collection by recovery system64.

In this embodiment, the generated cleaning solution typically forms asmall pool in front of the rotating cylindrical member 128 due to thecompression of outer cylindrical wall 136. While not wishing to be boundby theory, it is believed that the pooling provides a suitable path forconducting the acoustic waves (e.g., ultrasonic waves) from thetransducer(s) to the surface 18 being cleaned, through the dispensedcleaning solution. This is accordingly believed to provide suitablecontact for the generated cleaning solution to attract to and/ordislodge the contaminants (e.g., dirt) on surface 18 prior to beingdrawn back by the apertures in outer cylindrical wall 136. Thus, thecleaning solution generated by the combination of acoustic energy (e.g.,ultrasonic waves) and nanobubble generation is also suitable for usewith the compressible and rotatable cylindrical member 128.

As can be appreciated from the above embodiments, the solution generatordisclosed herein, which includes acoustic waves through a feed liquid(e.g., with an ultrasonic transducer), and generates nanobubbles in theliquid (e.g., with an electrolysis cell or other nanobubble generator),is suitable for use with a variety of different mobile floor cleaners.The resulting mobile floor cleaners are then capable of generatingcleaning solutions from aqueous liquids (e.g., water) that have goodcleaning capabilities without additives such as detergents, while alsoconsuming lower amounts of electrical power, for example. Thiscorrespondingly allows the mobile floor cleaners in some embodiments toincorporate smaller and/or fewer batteries with suitable operatingdurations.

While a solution generator according to the disclosure has generallybeen described in the foregoing as being implemented on a mobile floorcleaner, it should be recognized that other cleaning applications orapplication for cleaning are possible in accordance with the disclosure.As one example, the solution generator can be implemented on a cleaningwand or cleaning stick that can be grasp and manipulated by a humanuser. The user can control the cleaning stick to provide localizedcleaning to a soiled region, for example, treating pernicious soils notreadily released by mobile floor cleaner 10.

FIG. 16 illustrates an example cleaning stick 200 that is configured(e.g., sized and/or shaped) to be manipulated by a human user and thatincorporates a solution generator 54. Cleaning stick 200 may have anelongated shaft 202 that includes a handle portion 204 and a cleaninghead 206. The cleaning head 206 can carry a scrubbing brush, such asbristles, pads, or other fibers, that can be used to apply abrasivefriction to a surface to be cleaned. In addition, cleaning head 206 canhave one or more dispensing nozzles or orifices 208 through whichcleaning fluid is dispensed on a surface to be cleaned. In operation,the user can grasp the handle portion 202 of cleaning stick 200 andcontrol the stick to dispense cleaning fluid through dispensing orifice208 onto a surface to be cleaned. After dispensing the cleaning fluid orwhile dispensing the cleaning fluid, the user can physically move thecleaning stick to engage the scrubbing brush carried on cleaning head206 with the cleaning fluid dispensed on the surface to be cleaned. Thecombination of localized application of cleaning fluid with localizedscrubbing action can help remove pernicious soils, allowing an operatorto perform selective “spot” treatment where needed.

Solution generator 54 carried by cleaning stick 200 can be implementedusing any of the solution generator configurations described herein. Inone example, solution generator 54 includes a nanobubble generator and atransducer unit. The solution generator 54 receives liquid from areservoir, generates nanobubbles in the liquid, and applies acousticenergy to the liquid. The nanobubble generator can be implemented as anelectrolysis cell that generates the nanobubbles through electrolysisand/or a mechanical nanobubble generator that generates the nanobubbleswithout the application of electrical energy. The transducer unit canapply acoustic energy to the liquid upstream and/or downstream of thenanobubble generator. In another example, solution generator 54 includeseither a nanobubble generator or a transducer unit but not bothfeatures. Other configurations of nanobubble generator are possible asdescribed herein.

To control dispensing of cleaning liquid from cleaning stick 200, thestick can have user controls (e.g., switches, buttons, touchscreeninterface, etc.). An operator can interact with the user controls tocontrol solution generator 54, causing the solution generator togenerate cleaning liquid that is then dispensed on a surface at whichthe operator physically points cleaning head 206. In one example, theuser controls are positioned on handle 202 of cleaning stick 200.

In the example of FIG. 16, cleaning stick 200 is illustrated as beingtethered to mobile floor cleaner 10, which may or may not carry one ormore solution generators 54 as described above. Cleaning stick 200 canbe tethered to mobile floor cleaner 10 via one or more lines 210 thatprovide power and/or fluid to the cleaning stick. For example, cleaningstick 200 may be tethered to mobile floor cleaner 10 by a power linehaving an electrical conductor and providing electricity from a batterycarried by the mobile floor cleaner. Additionally or alternatively,cleaning stick 200 may be tethered to mobile floor cleaner 10 by a fluidline providing fluid communication between mobile floor cleaner 10 andsolution generator 56 carried on the cleaning stick. In operation,liquid can flow from a fresh liquid supply reservoir carried on mobilefloor cleaner 10, through fluid line 210, to solution generator 56carried on cleaning stick 200. If cleaning stick 200 is configured withfluid removal means (e.g., suction), a separate waste liquid line canprovide fluid communication between the fluid removal means and thewaste liquid reservoir carried on mobile floor cleaner 10.

Configuring cleaning stick 200 as a tethered unit to mobile floorcleaner 10 can be useful so that power and/or fluid utilized by thestick during cleaning operation are carried by mobile floor cleaner 10.This can reduce the weight of cleaning stick 200, making the stickeasier to use and more maneuverable by the operator. In addition,tethering cleaning stick 200 to mobile floor cleaner 10 can ensure thatthe stick stays in close proximity to the mobile floor cleaner. As theoperator is performing a cleaning operation using mobile floor cleaner10, the operator can readily access and use cleaning stick 200 to treatparticularly pernicious soils. In some such configurations, mobile floorcleaner 10 includes a mounting or carrying structure configured toreceive and hold cleaning stick 200 when the stick is not in use.

While tethering cleaning stick 200 to mobile floor cleaner 10 can beuseful to access power and/or fluid storage on mobile floor cleaner 10,in other configurations, cleaning stick 200 is not tethered to themobile floor cleaner. Rather, in these configurations, cleaning stick200 can have self-contained fluid and/or power. For example, handle 202of cleaning stick 200 can contain batteries for supplying power and/or afluid reservoir for supplying liquid to solution generator 54. This canallow cleaning stick to be readily portable to a wide range oflocations.

Although the present disclosure has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the disclosure.

1. A mobile floor cleaner comprising: a moveable housing; a cleaninghead operably supported by the moveable housing; a liquid sourceconfigured to provide a feed liquid; a conduit configured to relay thefeed liquid from the liquid source; one or more solution generatorsconfigured to receive the feed liquid from the conduit, and to generatea cleaning solution from the feed liquid by application of acousticenergy and nanobubble generation; and control electronics configured tooperate the one or more solution generators.
 2. The mobile floor cleanerof claim 1, wherein at least one of the solution generators comprises: atransducing unit configured to apply the acoustic energy; and at leastone of an electrolysis cell configured to generate the nanobubbles byelectrolysis and a mechanical nanobubble generator configured togenerate the nanobubbles through shear forces.
 3. The mobile floorcleaner of claim 2, wherein the acoustic energy comprises ultrasonicwaves.
 4. The mobile floor cleaner of claim 1, wherein the cleaning headcomprises a disc-type scrubbing brush, and wherein the mobile floorcleaner further comprises a motor configured to operably rotate thescrubbing brush.
 5. The mobile floor cleaner of claim 4, wherein the oneor more solution generators are secured to the cleaning head.
 6. Themobile floor cleaner of claim 5, wherein the cleaning head furthercomprises a cover for the scrubbing brush, and wherein the one or moresolution generators comprise a plurality of solution generators securedto the cover of the cleaning head.
 7. The mobile floor cleaner of claim5, wherein the one or more solution generators are secured to thecleaning head as one or more radial rows.
 8. The mobile floor cleaner ofclaim 1, wherein the one or more solution generators are arranged at alocation that is in front of the cleaning head in a primary direction ofmovement of the mobile floor cleaner.
 9. The mobile floor cleaner ofclaim 8, wherein the one or more solution generators comprise aplurality of the solution generators arranged in a row.
 10. The mobilefloor cleaner of claim 1, wherein the cleaning head comprises arotatable cylindrical member having a compressible outer surface, andwherein the one or more solution generators are located inside of therotatable cylindrical member.
 11. A method for cleaning a surface, themethod comprising: providing a mobile floor cleaner having a cleaninghead and a solution generator; directing a flow of a feed liquid to thesolution generator; generating a cleaning solution by applying acousticenergy to and generating nanobubbles in the feed liquid in the solutiongenerator; dispensing the generated cleaning solution to the surface;and agitating the dispensed cleaning solution with the cleaning head.12. The method of claim 11, wherein applying the acoustic energy isperformed prior to generating the nanobubbles.
 13. The method of claim11, wherein generating the nanobubbles is performed prior to applyingthe acoustic energy.
 14. The method of claim 11, wherein applying theacoustic energy to the feed liquid comprises inducing ultrasonic wavesthrough the feed liquid.
 15. The method of claim 11, wherein generatingthe nanobubbles in the feed liquid comprises conducting electrolysis onthe feed liquid.
 16. A mobile floor cleaner comprising: a moveablehousing; a liquid source configured to provide a feed liquid; a conduitconfigured to relay the feed liquid from the liquid source; a scrubbingbrush operably supported by the moveable housing, wherein the scrubbingbrush comprises: a backing portion; one or more sub-units eachconfigured to retain a set of bristles; and one or more transducerssupported by the backing portion and configured to vibrate the one ormore sub-units and retained sets of bristles; and control electronicsconfigured to operate the one or more transducers.
 17. The mobile floorcleaner of claim 16, further comprising one or more solution generatorsconfigured to receive the feed liquid from the conduit, and to generatea cleaning solution from the feed liquid by application of acousticenergy and nanobubble generation.
 18. The mobile floor cleaner of claim16, further comprising a motor configured to rotate the scrubbing brush.19. The mobile floor cleaner of claim 18, further comprising one or moresolution generators configured to receive the feed liquid from theconduit, and to generate a cleaning solution from the feed liquid byapplication of acoustic energy and nanobubble generation.
 20. The mobilefloor cleaner of claim 16, wherein the one or more transducers areconfigured to vibrate the one or more sub-units and retained sets ofbristles at an ultrasonic frequency.